The Real-time Image Edge Detection Based On Sobel Operator System Design

Edge detection technology is one of the most important techniques of the digital pictureprocessing technique, which is widely used in product detection, traffic control, nationaldefense security, biomedicine and other fields. Therefor，it is of prime importance to use andresearch for edge detection of image processing system, which is real-time, accurate, stableand flexible.Under this circumstance, edge detection system arises. FPGA is out of other hardwareprocessor for its unique logic structure, abundant storage resources，timeliness，high reliabilityand etc. This thesis ‘s analysis and research are based on the mainstream of edge detectionoperator and FPGA processing chips. For the purpose of implementation of real time edgedetection of dynamic human body image, and design the edge detection system for humangait video images which is based on Sobel operator.In this thesis, image-processing system is designed for two parts, external functionalhardware and internal logic function device. External hardware mainly includes the cameraand LCD screen that is used for real-time display. While the internal logic function device ismainly composed of acquisition function module, cache function module, edge detection offunction module and display module.Among them, the main function of image acquisition function module is turn the analogvideo signal through A/D decoding into a digital video signal which is accordance with PAL,can be identified and operated. The main task of the cache function module is make theprocessing video data input video encoding chip after reading, writing and caching operationsto the digital video signal. In the edge detection function module，this system uses the Sobel operator which has strong real-time, high precision, low implementation difficulty toaccomplish the image edge detection. After experimental verification, the operator can ensurethe detection accuracy, at the same time improve the real-time performance of the systemutmostly. Display function module is for the purpose of strengthening man-machineinteraction and improving the visual effect, by using D/A converter and VGA interface todisplay after edge detection and extraction of image real-time the results. After implementauthentication， on the one hand Sobel operator can ensure the detection accuracy, on theother hand it also can maximum the real-time performance of the system.This article uses the Altera Company’s EP4CE FPGA chip which is belongs to theCyclone IV series as the core processor, uses the Verilog hardware description language todesign every module and takes the Altera Cyclone II EP4CE FPGA chip as the core processor,also verifies the experiment by QuartusII12.1platform provided by Altera. The rate of thissystem is to capture the input video image in25frames per second. The FPGA control thedata at a rate of about40MHZ to read from SDRAM and display from VGA. Finally outputresolution is800600images.